The objective of this program project is the application of positron emission tomography in the in vivo assessment of metabolic pathways in various organs specifically the brain, heart and lungs. the approach is to develop methods for the in vivo regional measurement of physiological parameters and to extend this knowledge to the understanding of basic biological processes in normal and diseased states. Compounds are labeled with the positron emitting radionuclides, oxygen-15, carbon-11 or fluorine-18 using radionuclides. These radionuclides are then combined into radiopharmaceuticals which can either measure flow, metabolism or other physiological parameters. These radiopharmaceuticals are then administered to animals or human subjects and used to measure in vivo function.